Corrosion behaviors of zinc and Zn-Ni alloy compositionally modulated multilayer coatings

Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited from dual baths. The coated samples were evaluated in terms of surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The results obtained from the salt spray test show that the zinc and Zn-Ni alloy CMM coatings are more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy alone with a similar thickness. The corrosion potential measurement and anodic polarisation tests were undertaken to examine the probable corrosion mechanisms of zinc and Zn-Ni alloy CMM coatings. Analysis on the micrographic features of zinc and Zn-Ni alloy CMM coatings after the corrosion test explains the probable reasons why the Zn-Ni/Zn CMM coatings have a better protective performance. Surface morphologies and compositional analysis of the remaining coating material of Zn-Ni alloy deposit after the corrosion test confirms the dezincification mechanism of the Zn-Ni alloy deposit during the corrosion process.     

Corrosion Performance of Zinc and Zinc-cobalt Alloy Compositionally Modulated Multilayer （CMM） Coatings

Varieties of zinc and Zn-Co alloy compositionally modulated multilayer （CMM） coatings were electrodeposited onto steel substrates using dual bath technique. The surface and cross-sectional morphologies of coated samples were examined using scanning electron microscopy （ SEM ）. The existence of iuternal stress in ZnCo alloy deposits was confirmed by the cross-sectional morphalogies for the occurrence of micro-cracks in the thick Zn-Co alloy deposit alone. The corrosion performance was evaluated using neutral salt spray testing, corrosion potential measurement and anodic polarization methods. The experimental results slum, that the zinc and Zn- Co alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Co alloy alone with a similar thickness. The analysis on the micrographic features of zinc and Zn-Co alloy CMM coatings, using field emission gun scanning electron microscopy （FEGSEM） after corrosion testing, explains the probable reusons why the Zn-Co/ Zn CMM coating system has a better protective performance.     

电沉积铅合金在硫酸中循环伏安行为的研究

采用循环伏安法研究了铜上电沉积铅锡合金和铸造的铅合金在硫酸中的电化学行为,并且在多次循环后,比较两种电极的循环伏安曲线及表面形貌．结果表明：在硫酸电解液中,铜上电沉积铅锡合金电极表面发生的主要电化学反应,与铸造铅电极表面发生的主要的电化学反应基本相同,多次循环后电沉积铅锡合金电极具有更加均匀的表面形貌和组织结构．     

Isothermal corrosion Fe3Si alloy in liquid zinc

1. Introduction In continuous hot-dip coating lines, the immersed bath hardware (e.g. bearings, sink, stabilizer, and cor- rector rolls, and also support roll arms and snout tip) is subject to corrosive attack by the molten bath material. In the series of…     

高强度稀土锌基模具合金的研制

研究了不同成分的锌基合金的强度，并在此基础上探讨了不同稀土元素对锌基合金性能的影响，得到了一种高强度稀土锌基合金，并对其强化机理进行了初步分析。     

Preparation and characterization of novel porous Fe-Si alloys

Porous Fe-Si alloys with different nominal compositions ranging from Fe-10wt% Si to Fe-50wt% Si were fabricated through a reactive synthesis of Fe and Si elemental powder mixtures. The effects of Si contents on the pore structure of porous Fe-Si alloy were investigated in detail. The results showed that the open porosity, gas permeability and maximum pore size of the porous Fe-Si alloys increased with increasing Si contents, indicating that the porosity and pore size can be tailored by changing the Si contents. The pore structure parameter including the open porosity, gas permeability, maximum pore size obeyed the Hagen-Poiseuille formula with the constant G=0.035 m^-1Pa^-1s^-1 for the reactively synthesized porous Fe-Si alloys. The mechanical property of the porous Fe-Si alloys showed applicability in the filtration industries.     

片状锌粉的可控钝化及电性能研究

采用水/酒精、双氧水溶液为氧化剂,制备了表面钝化Zn(OH)2的片状锌粉.采用X射线衍射(XRD)、热重分析(TG)、扫描电镜(SEM)对钝化锌粉进行了表征,考察了钝化增重对锌粉压片电阻率和漏电流密度的影响.结果表明,锌粉钝化后在表面形成鼓包状组织,随着氧化剂浓度和时间的增加,锌粉钝化增加;随着钝化膜的增厚,钝化锌粉的电阻率增加,漏电流密度减小.     

磷化液中ZnO对AZ61镁合金磷化膜的影响

探讨了锌系磷化液中主要的成膜物质ZnO的质量浓度对AZ61镁合金磷化膜的微观结构和性能的影响.利用金相显微镜、扫描电镜、能谱分析仪观察和分析了磷化膜的结构、表面形态和组成成分,并通过阳极极化曲线测量评价了磷化膜的耐腐蚀性能.结果表明:在低ZnO质量浓度的磷化液中,获得的磷化膜比较疏松且不完整,其并未表现出优异的耐腐蚀性;在高ZnO质量浓度的磷化液中,得到的磷化膜晶粒较粗大,厚度不均匀,耐腐蚀性不佳;在中等ZnO质量浓度2.0g／L的磷化液中,得到了均匀、完整的磷化膜层,极化曲线测量表明了其在质量分数为3.5％NaCl溶液中具有较好的耐腐蚀性.     

合金粉和注液量对镍氢电池性能的影响

研究了不同钴含量的合金粉以及注液量对镍氢电池放电容量、内阻、过充性能和大电流(4A)放电性能的影响.实验结果表明,合金粉的钴含量对内阻的影响不大,钴的质量分数为6.0%合金粉的1C放电容量要好于钴的质量分数为5.5%的合金粉,但过充性能和大电流放电性能却低于钴的质量分数为5.5%合金粉;随着注液量的增加,放电容量、内阻、过充性能和大电流(4A)放电性能均有所提高.但注液量过高,过充性能会有所下降.     

火焰原子吸收光谱法测定营养品及海产品中的金属元素

测定几种常见市售营养品、海产品中一些金属元素的含量,为人们选购进补食品提供参考。湿法消化样品,采用火焰原子吸收方法测定各元素的含量,并改进了赶酸方式。实验测定了藕粉、豆粉、芝麻糊、核桃粉、虾皮、海米及干鲜蛤蜊中Ca,Mg,K,Fe,Zn的含量。结果表明：海产品中,虾皮各元素含量较高,其中Ca含量达12 200μg/g;营养品中,豆粉各元素平均含量最高。建议虾皮、豆粉可以作为全面营养品的首选。     

W对Co基合金熔覆层组织和耐锌蚀性能的影响

为了提高热镀锌生产线关键部件的使用寿命并节约热镀锌成本,采用半导体激光器在316L不锈钢表面制备了具有不同成分的两种钴基合金熔覆层.分别对激光熔覆层的组织形貌、成分、相结构、显微硬度及耐锌蚀性能进行了研究.结果表明,W元素的加入使得熔覆层晶粒发生细化,熔覆层组织主要由γ-Co固溶体、Co_3Mo_2Si相和少量Cr_7C_3相组成,同时还生成了少量弥散分布的Co_6W_6C相.添加W元素后熔覆层的平均硬度可达986 HV,相比未添加W元素的Co基合金熔覆层约增加了114 HV,且约为316L不锈钢的4.5倍.与原Co基合金熔覆层相比,添加了W元素的Co基合金熔覆层中弥散分布的Co_6W_6C相使熔覆层耐锌蚀性能大幅度提高.     

Corrosion resistance of cerium conversion film electrodeposited on Mg-Gd-Y-Zr magnesium alloy

The cerium conversion film was applied to improving the corrosion resistance of Mg-Gd-Y-Zr magnesium alloy. The film was electrodeposited on the surface of the Mg-RE alloy in cerium nitrate solution. The compositions and morphologies were analyzed by X-ray diffraction(XRD), scanning election microscopy (SEM). The corrosion behaviors of the film were investigated electrochemical impedance spectroscopy (EIS), potentiodynamic polarization tests and immersion tests. The results show that the optimum parameters for electrochemical deposition are as follows: pH 10.0, time 30 min, 50 mmol/L Na₂CO₃ and temperature 25 °C by the designed experiments according to the orthogonal table L(9, 3⁴). The corrosion protection efficiency is dependent on the deposition parameters. The cerium conversion film shows better corrosion protection behavior than chromate conversion film on Mg-Gd-Y-Zr magnesium alloy. Foundation item: Project (5133001E) supported by the Major State Basic Research and Development Program of China     

稀土对激光熔覆Co基合金组织及性能的影响

为了提高热镀锌生产线关键部件的使用寿命,采用激光熔覆技术在316L不锈钢表面制备了具有不同稀土氧化物含量的Co基熔覆层.利用扫描电子显微镜、能谱仪、X射线衍射仪和显微硬度计研究了稀土氧化物对Co基合金熔覆层显微组织、相结构、显微硬度的影响.结果表明,稀土氧化物使得Co基合金熔覆层的组织更为细化,且硬度更高.添加质量分数为0.5%的CeO_2后,Co基合金熔覆层的显微硬度高达900 HV.Co基稀土合金熔覆层主要由γ-Co、Cr_7C_3及相应稀土氧化物组成.稀土氧化物的加入有效延缓了由锌液沿微裂纹扩展引起的溶解腐蚀.添加质量分数为0.5%的CeO_2后,Co基合金熔覆层的腐蚀深度约为12μm,锌蚀过渡层平直且完整,耐锌蚀性优异.     

纳米CuAl2的制备及其结构表征

根据ICF靶材料研究的需要,采用自悬浮定向流法制备了金属间化合物CuAl2纳米复合微粉,并通过TEM和XRD等分析手段对复合微粒材料的显微结构和相组成进行了研究。结果表明,所制备的纳米复合颗粒呈规则的球形,粒径分布在30～50 nm之间,颗粒的主要组成相为CuAl2,并有少量的Al和Cu9Al4存在。结合自悬浮定向流技术的基本原理,发现生成金属间化合物的类型与制备过程中金属蒸气的成分有关,两者的原子分数有相应的对应关系。     

镁合金表面HA/CNTs涂层的制备及电化学性能研究

为了提高生物镁合金羟基磷灰石(HA)涂层的耐蚀性能,在微弧氧化电解液中加入羟基磷灰石/碳纳米管(HA/CNTs)复合粉体添加剂,制备HA/CNTs复合涂层。分别对制备的HA/CNTs复合粉体和HA/CNTs复合涂层进行表面形貌和物相组成分析,并对HA/CNTs复合涂层在模拟体液(SBF)中的耐腐蚀性能进行了研究。结果表明,HA/CNTs复合粉体在微弧氧化过程中能均匀地沉积在镁合金表面,结晶良好且无任何杂质;与HA涂层相比,HA/CNTs涂层具有较小的腐蚀电流密度值和较大的阻抗值。此外,在SBF中浸泡4d后,HA/CNTs复合涂层表面出现大量的亚微米级颗粒产物且没有任何腐蚀裂纹。     

铜基防振合金的高阻尼特性

采用电解铜、电解锰、电解锌、工业纯铝为原料,熔制了不同成分的Mn—Cu系合金及Cu—Zn—Al合金,并测试了其在不同初始应力下的减振能力。结果表明:此类合金的工作应力只有超过各自的临界应力才能发挥其高阻尼性能;含有适量Zn、Al的Mn—Cu合金具有较高的阻尼性能,是优良的减振材料。     

金属锌电沉积的分形研究

以环形金属锌板作为阳极,石墨棒作为阴极,对电沉积过程中金属锌的二维枝晶生长进行了研究,并对不同电沉积条件下所得到的沉积产物的分形维数和宏观形貌进行了观察、分析.研究表明,随外加电压的升高,金属锌二维沉积产物的形貌由开放的枝状晶向致密的粗大枝晶转变,分形维数也呈增大趋势;随着电解质溶液中硫酸锌浓度的增加,阴极沉积产物先后出现了类似于DLA模型模拟结果的枝状形貌、具有分叉结构的致密纤维状枝晶簇和较为粗壮的开放型规则分叉状枝晶等不同形貌,分形维数亦随之发生相应的改变.     

镁合金镀镍磷合金及无铬前处理工艺

AZ91D镁合金首先在无铬的磷酸盐溶液中磷化,然后在硫酸盐镀液中镀镍磷合金。用SEM和XRD对磷化膜的化学组成及微观结构进行了表征,探讨了磷化膜及镍磷合金镀层的形成机理。结果表明:磷化膜主要由Zn3(PO4)2.4H2O和单质锌组成,金属锌粒子作为进一步镀镍磷合金的形核催化剂;磷化液中的间硝基苯磺酸钠使磷化膜的一部分微阳极区变为微阴极区,增加了磷化膜的成膜速度并细化了磷化膜结晶;在含4.0 g/L间硝基苯磺酸钠的磷化液中得到的磷化膜上沉积的镍磷合金镀层致密均匀,有较高的耐蚀性,镀层的附着强度符合ISO 2819的要求。     

Electrodeposition of Ni-Cr alloy on aluminum substrate

1 INTRODUCTIONOwing to low mass , high strength and easymachining, aluminum ( Al) and its alloys havebeen widely appliedin many fields .But the chemi-cal character of Al is very active ,it can be oxidizedeasilyinthe at mosphere and erodedinthe foul con-dition,and its wear resistance is poor . All theseseriously affect its application andlifeti me .It is aneffective protective measure to i mprove perform-ance by means of plating alloy on Al substrate .Ni-Cr alloys have many characteristi…     

Preparation of β-Sialon/ZrN bonded corundum composites from zircon by nitridation reaction sintering process

β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum, alumina micro powder, zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the synthesized composites were investigated by X-ray powder diffraction and scanning electronic microscope, and the formation process of the composites was discussed. The results show that the composites with different compositions can be obtained by controlling the heating temperature and contents of zircon and carbon black. The proper temperature to synthesize the composites is 1 773 K.